this post was submitted on 17 Feb 2024
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Showerthoughts

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If a machine is never 100% efficient transforming energy into work because part of the energy is converted into heat, does it mean an electric heater is 100% efficient? [@showerthoughts@lemmy.world](h (social.graves.cl)
submitted 9 months ago by alvaro@social.graves.cl to c/showerthoughts@lemmy.world
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If a machine is never 100% efficient transforming energy into work because part of the energy is converted into heat, does it mean an electric heater is 100% efficient? @showerthoughts@lemmy.world

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[–] orcrist@lemm.ee 4 points 9 months ago (1 children)

This is discussed in many places, but you are here, so let's do it... A heater that consists of a resistance element is turning nearly all of the electricity into heat. Around 100% efficiency. But if it has an LED and fan, then maybe 5% (or less?) of that electricity is used for those, so it's easy only 95% (or more?) efficient.

That is how those terms are defined in this context. How much heat is produced by a resistance heater using one watt? That's a known quantity, and we use it to compare against other heating sources.

And it makes sense to use this number if you are comparing to wood or gas or coal or oil heat, where some goes out the chimney, or to heat pumps, where things are a lot more complicated.

[–] threelonmusketeers@sh.itjust.works 1 points 9 months ago (1 children)

it has an LED and fan

If you can't see the light or hear the fan from outside the room you are using the heater in, that energy has also become heat.

[–] Xeroxchasechase@lemmy.world 1 points 9 months ago (1 children)

Yeah, but than, does it really makes a sound?

[–] threelonmusketeers@sh.itjust.works 2 points 8 months ago (1 children)

At the expense of ruining the joke, yes it does. Anyone inside the room would be able to hear the sound.

And if no one is in the room to hear if there is a sound or not, you might want to turn the heater off to conserve energy.

[–] Xeroxchasechase@lemmy.world 1 points 8 months ago

Oh I didn't think of it!